A cDNA clone specific for the oligodendrocyte-derived extracellular matrix glycoproteins J1-160/180 was obtained from a lambda ZAPII expression library using polyclonal antibodies generated against mouse J1-160. The library was constructed from poly(A)(+)-RNA isolated from O1 antigen-positive rat oligodendrocytes. The cDNA clone expressed a fusion protein that was recognized by the J1-160/180-specific monoclonal antibodies 596, 619, and 620, and, weakly, 597. The fusion protein was not recognized by polyclonal antibodies to mouse J1/tenascin. The cDNA clone with an insert of approximately 5.6 kb in size contained the nucleotide sequence coding for the amino acid sequence of the N-terminus of a tryptic peptide derived from mouse J1-160. The developmental and tissue distribution of the mRNA recognized by the cDNA clone is in agreement with the described expression of the J1-160/180 proteins.